The present invention relates to a characteristic test apparatus for an electronic device, which can evaluate the characteristics of an electronic device, e.g., an LSI, a VLSI, a discrete 3-input active element, or the like, or can detect failure during the step of manufacture (i.e., in an in-process state) of such an electronic device.
For an electronic device of this type, a finished electronic device is examined to evaluate its characteristics. However, as the manufacturing process of the device becomes complicated, the characteristics of the device during the manufacturing process often considerably influence those of a finished product. In particular, in a micropatterned, complicated electronic device such as an LSI or a VLSI, testing of the device during the manufacturing process is mandatory, and a need has arisen for development of such a test apparatus.
Conventionally, an electron beam tester using an electron beam having a high spatial resolution has been developed for a test apparatus for a micropatterned, complicated electronic device. In this test apparatus, an IC chip of the electronic device is placed on a test table, and a test bias signal is applied from an IC drive unit through the external terminal of the electronic device. Upon application of the test bias signal, the pattern of the electronic device on the IC chip is scanned, and a voltage at a predetermined position of the electronic device is then measured, thus obtaining data necessary for characteristic evaluation of the electronic device. Such a test apparatus is explained in detail in, e.g., "ELECTRON BEAM TEST TECHNIQUES FOR INTEGRATED CIRCUITS", Scanning Electron Microscopy, 1981, Vol. 1, p. 305.
In such a test apparatus, however, in order to supply the test bias signal, an external terminal pad electrode for supplying the test bias signal to the electronic device must be arranged at an appropriate position of the IC chip, and this electrode occupies a large area of the IC chip relative to the circuit pattern of the electronic device. Therefore, this interferes with decreasing of a space factor of an IC element aiming at a high integration density. Still more, the electronic device must be functionally finished to a state immediately before packaging. Therefore, it is impossible to evaluate the characteristics of the electronic device during its manufacturing period using this test apparatus.
In order to solve the above problems, another test apparatus has been developed. This test apparatus locally radiates a charged beam onto an electronic device, and evaluates the presence/absence of gate leakage or disconnection of metal wirings by detecting secondary electrons from the irradiated position or other position of the device using a secondary electron detector. Such an apparatus is described in, e.g., Japanese Patent Prepublication No. 57-196540 and Japanese Patent Publication No. 45-8820. However, with this apparatus, a secondary electron signal is detected only for evaluation. Thus, a potential of the charged beam at the irradiated point varies over time and cannot be maintained constant, thus preventing a quantitative characteristic test.